Yet, I cannot interrupt the Casting Frontswing of both with simple movement commands on W3 DotA. On the other hand, HoldPosition and Stop commands do interrupt the Casting Frontswing, but this applies for every spell that has a Casting Frontswing.

Also, the Unstable Concoction Start is impossible to interrupt, at least I can't, so I think it has no frontswing at all...

Yep, I kinda forgot to go back to Alchemist as I went down the list of heroes, didn't realise the mistake. I meant to type "N/A" in the "cancellable during" field (both CA and BS) for spells that have no backswing (because they do not need to be cancelled), which includes Acid Spray.

Unstable Concotion Start indeed has no frontswing but has a backswing - this is evident because Alchemist stops as soon as the spell is cast, and can be quickly cancelled if you press E and right click somewhere. Other similar spells include Troll and CW's ultimates.

Shadow Demon:
Soul Catcher and Shadow Poison is fixed,
Shadow Poison Release is still instant (wrong), and in addition stutters after casting as if he has a very short backswing

Timbersaw:
Timber Chain is fixed,
Whirling Death is supposed to have a backswing. Return Chakram is still instant (correct) but stutters after casting as if he has a very short backswing. Correct behavior = no frontswing and no backswing

Unsure:
Pudge
Sand King

They both feel the same. Anyway, previous tests showed that they were already consistent with their wc3 counterparts.

Fixed some stuff in the doc previously wrongly labelled:
Dota 2 Leshrac's Pulse nova was given a green box but text that said YES. He doesn't have a cast time for that one, fixed the text.
Spirit Breaker's Nether Strike is supposed to have no backswing, so you can attack nearby targets once you cast it as you were "fading". Labelled it wrongly as "ATTACKS TARGET" when it has a backswing. It's fixed now (has no backswing) in the main client.

Also invoker;in dota 1, if you shift queue one of his skills such as meteor + blast combo and shift move, he still keeps on moving without stopping. While in dota 2, he stops and cast that skill then continue moving.